The present invention relates to an image distortion correcting apparatus for a television camera.
In a telvision camera incorporating an image pickup tube or imaging tube, it is known that distortion of high degree takes place in deflection due to nonuniformity among the imaging tube, deflecting coils, deflecting circuits and others. Such distortion has heretofore been compensated for or corrected by using a combination of a correcting waveform of low degree produced by an analogue type correcting circuit and a correcting waveform of high degree produced by a digital type correcting circuit. However, correction of this type involves an increase in the amount of data for correction because all the distortions of high degree are corrected through digital processing. More specifically, in order to realize the correction of distortion with a high accuracy, the number of bits used in a unit of data for correction has to be increased to thereby prevent occurrence of distortion of higher degree and shading due to distortion being partially left uncorrected. To this end, an imaging plane (the scanning area of the target in an image pickup tube) must be divided more finely for the digital correction. As a disadvantageous consequence, a large amount of data for the correction, increasing of the circuit scale and a higher processing speed are required. Of course, these disadvantages can be obviated by decreasing the amount of data for correction. In that case, however, difficulty is encountered in realizing a satisfactory accuracy of correction, to another disadvantage.